Why didn’t they just
Get the original cast members to play themselves? Sure they would have aged a bit but as we know from The Irishman, CGI can de-age a person. Heck Francis Ford Coppola was able to make Marlon Brando look like a 70 year old man, even a good makeup artist would have been able to make them look like they did in the 1950’s.
Just recasting the actors totally took me out of the movie.